Li Wei, Wang Yaomei, Chen Lixiang, An Xiuli
School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China.
Laboratory of Membrane Biology, New York Blood Center, New York, NY 10065, USA.
Blood Sci. 2019 Sep 17;1(1):61-64. doi: 10.1097/BS9.0000000000000017. eCollection 2019 Aug.
Erythroblastic island (EBI), composed of a central macrophage surrounded by developing erythroid cells, is a structure found in hematopoietic tissues such as fetal liver and bone marrow. It is the first described hematopoietic niche that predominantly supports erythropoiesis. Although it is well accepted that EBIs and EBI macrophage play important roles during erythropoiesis, the mechanisms by which they support erythropoiesis remain largely unclear due to our inability to identify and isolate EBI macrophages. Earlier efforts to identify surface markers for EBI macrophages have focused on the adhesion molecules which are involved in macrophage's interaction with erythroblasts. These include EMP, Vcam1, CD169, CD163, and αV integrin. Findings from these earlier studies suggested that combination of Vcam1, CD169, and mouse macrophage surface marker F4/80 can be used to define mouse EBI macrophage. We found that not all F4/80Vcam1CD169 macrophages are EBI macrophages. Instead, we discovered that EBI macrophages are characterized by the expression of Epor in both mouse and man. RNA-seq analyses of the newly identified EBI macrophages revealed that EBI macrophages have involved specialized function in supporting erythropoiesis. Our findings provide foundation for future studies. Here we will review current knowledge of EBI macrophages and discuss future perspectives.
红细胞生成岛（EBI）由一个被发育中的红细胞包围的中央巨噬细胞组成，是在胎儿肝脏和骨髓等造血组织中发现的一种结构。它是最早被描述的主要支持红细胞生成的造血微环境。尽管人们普遍认为红细胞生成岛和红细胞生成岛巨噬细胞在红细胞生成过程中发挥重要作用，但由于我们无法识别和分离红细胞生成岛巨噬细胞，它们支持红细胞生成的机制在很大程度上仍不清楚。早期识别红细胞生成岛巨噬细胞表面标志物的努力主要集中在参与巨噬细胞与成红细胞相互作用的黏附分子上。这些分子包括EMP、Vcam1、CD169、CD163和αV整合素。这些早期研究的结果表明，Vcam1、CD169和小鼠巨噬细胞表面标志物F4/80的组合可用于定义小鼠红细胞生成岛巨噬细胞。我们发现并非所有F4/80Vcam1CD169巨噬细胞都是红细胞生成岛巨噬细胞。相反，我们发现红细胞生成岛巨噬细胞的特征是在小鼠和人类中均表达促红细胞生成素受体（Epor）。对新鉴定的红细胞生成岛巨噬细胞的RNA测序分析表明，红细胞生成岛巨噬细胞在支持红细胞生成方面具有特殊功能。我们的发现为未来的研究提供了基础。在此，我们将综述目前关于红细胞生成岛巨噬细胞的知识，并讨论未来的研究前景。
